A novel degradation mechanism of the elastic modulus of wet polymer substrates under nanoindentation.
Soft Matter
; 16(21): 5009-5019, 2020 Jun 07.
Article
em En
| MEDLINE
| ID: mdl-32436554
ABSTRACT
We demonstrated that the formation and solidification of a continuous confined water film played a very important role in changing the elastic modulus of the wet polymer substrate in a nanoindentation process by a coarse-grained molecular dynamics simulation of this process. It was found that as the water content increased, the elastic modulus of the wet polymer substrate showed a non-monotonic change. Relative to the dry polymer substrate, the elastic modulus of the wet polymer first decreased. This is because the appearance of a confined water film caused the force between the polymer substrate and the indenter to change from repulsion to attraction. Subsequently, as the confined water film gradually solidified and then weakened, the elastic modulus of the wet polymer slowly increased and then rapidly increased due to a large number of interstitial water molecules gradually penetrating the polymer substrate. Therefore, it is unreasonable to explain the wet polymer degradation during nanoindentation only from the plasticization and anti-plasticization effects based on the hydrogen bond breaking and formation during stretching. The above-mentioned results will help to more comprehensively understand the degradation mechanism of the polymers' encounter with water, thus promoting further practical applications for polymers.
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Base de dados:
MEDLINE
Idioma:
En
Revista:
Soft Matter
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
China